1000 extra cars on the local roads during rush hour

Please find attached (KKG Document 11) an abridged version of the Traffic Feasibility Study for the development at Kempton Park.

In order to reduce the size of the file, we have omitted Appendices F and H, which contain pages of data output from the transport model used by Mouchel.

The forecast extra traffic numbers during peak hours from a development of 1500 units at Kempton Park are on page 3 of Appendix C. During the AM peak, an extra 979 vehicles are forecast to travel in one direction or the other along the A308 between Sunbury Cross and Hampton Court. Given that car ownership in Sunbury is two per household or more, this appears to be a low estimate. Even so, Mouchel assume approximately 1000 extra cars on the local roads during rush hour …

The forecast distribution of these cars on the local road network during the AM peak is shown on the diagram D013 on page 5 of Appendix C. 78% of the extra traffic is forecast to turn right out of the proposed suburb of 1500 units at Kempton Park during the AM peak, and travel towards Sunbury Cross. This entrance/exit would in itself reduce the traffic flow on the A308, as the right-turning (westbound) traffic during the AM peak would have to turn in front of traffic travelling eastbound towards Hampton Court, and join the peak hour queue of traffic traveling westbound towards Sunbury Cross.

20% of cars from Kempton Park are assumed to turn left during the AM peak and travel in the other direction towards Hampton Court and beyond – to Richmond, Kingston and across Hampton Court Bridge towards the A3.

This distribution of the extra Kempton Park traffic is based on an assumption that the employment and lifestyle characteristics of the residents of the new suburb at Kempton Park will mirror those of the existing residents of Sunbury East. The Borough of Richmond, however, asked Mouchel to run the simulation again, but this time using the employment and lifestyle characteristics of the residents of Hampton Ward, our neighbours on the eastern edge of Spelthorne. The result are shown in diagram 1048911-D016-D01A in Appendix D.

Assuming that the residents of the new suburb behave more like residents of Hampton than Sunbury East, the extra traffic towards Sunbury Cross in the AM peak would only account for 2/3 of the total. Nevertheless, although traffic joining the (southbound) M3 is forecast to be significantly less, traffic on the (northbound) A316 would be more than 20% higher.

The remaining third would travel towards Hampton Court. The extra volume of traffic turning left at the Hampton Triangle would be more than triple (17% of the total as opposed to 5%) the number forecast to take that route under the Sunbury East assumption. The extra traffic volume travelling along the side of Hampton Court towards Kingston would be more than 40% bigger.

So, the traffic gets significantly heavier than it already is in both directions, with the direction of travel worst affected depending on how the new residents behave. And this would be on a ‘normal’ day. Don’t forget the week of the Hampton Court Flower show, and all the other events during the year which already cause very heavy traffic congestion on local roads on a regular and frequent basis.

Mouchel have been searching for ways to add this extra traffic to the local roads without causing a permanent gridlock. Hence the proposed massive redevelopment of Sunbury Cross (see KKG – Document 2 sent previously), and hence the proposed reworking of the traffic arrangements at the Hampton Triangle (Appendix G in KKG – Document 11) and the Hampton Court roundabout (Appendix E in KKG – Document 11). The proposed schemes don’t give us any confidence that they could make much of a difference to the existing over-burdened roads, never mind with the extra burden of a new suburb at Kempton Park.

As ever, these documents are in the public domain. Please feel free to pass them on.